- Primary Outcome: Diagnostic accuracy.
- Sensitivity, specificity, positive predictive value, and negative predictive value were all 100 percent (95% CI, 87–100).
- Secondary Outcomes:
- 25/65 (38 percent) had fractures, with 13 Hill-Sachs/Bankart.
- Non–Hill-Sachs/Bankart fracture: Sensitivity 92 percent (95% CI, 60–99.6), specificity 100 percent (95% CI, 92–100), positive predictive value 100 percent (95% CI, 68–100), and negative predictive value 98 percent (95% CI, 89–99.9).
- POCUS was 43 minutes faster from exam to diagnosis compared to X-ray.
- The median glenohumeral distance was –1.83 cm (interquartile range [IQR] –1.98 to –1.41 cm) in anterior dislocations, 0.22 cm (IQR 0.10–0.35 cm) on nondislocated shoulders, and 3.30 cm (IQR 2.59– 4.00 cm) in posterior dislocations.
- Sonographers’ confidence in their POCUS diagnosis was 9.1 of 10 in nondislocated cases and 9.4 of 10 in dislocated cases.
Evidence-Based Medicine Commentary
- Convenience Sample: The study did not recruit consecutive patients but rather a convenience sample when one of six sonographers were available. There is a potential for selection bias with this type of sampling.
- Missing Data: All 32 patients with dislocations were supposed to have had a post-reduction POCUS performed. However, in five cases, this did not happen. The manuscript says it was because the study sonographer was unavailable after the reduction for various reasons without further explanation. This could have introduced some bias and increases our skepticism of the results.
- Missed Fractures: Twenty-five of 65 patients had fractures (38 percent). POCUS identified only 52 percent of those fractures. However, all but one of the missed fractures was a Hill-Sachs deformity or a Bankart lesion. Hill-Sachs and Bankart fractures are generally not relevant to the emergency management of patients with shoulder dislocations. POCUS was 92 percent sensitive (95% CI, 60–99.6%) and 100 percent specific (95% CI, 92–100%) for non–Hill-Sachs/Bankart fractures. This miss rate of 8 percent of non–Hill-Sachs/Bankart fractures is too high for American medicine.
- External Validity: Although the study was technically multicenter because two facilities were involved, one of the two sites enrolled only five patients. In addition, ultrasound fellows or ultrasound fellowship-trained attendings performed the scans. This makes us question the external validity of the study. If the ultrasounds were performed by typical community emergency physicians, we are unsure the same impressive results would be achieved.
- Time Saved: The median time to POCUS from triage was 51 minutes (IQR 36–77) compared to 101 minutes (IQR 73–134) for X-ray. The amount of time saved in the real world would depend on the system in which the physician is working. In a facility with single-physician coverage, the X-ray tech may complete the X-ray before the physician has an opportunity to perform an ultrasound. Last, they did not provide information on total ED length of stay.
X-rays should continue to be the primary imaging modality of choice for most patients with suspected shoulder dislocations.